Add caching

6 files changed, 146 insertions, 4 deletions

diff --git a/README.md b/README.md
index db923fc..330e913 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,9 @@ Here is a commented example config. For more details, consult the documentation
 	# This config key defines the default storage backend, as defined below
 	default_storage = "local_encrypted"
 
+	# This defines the location of the cache file (can speed up creating backups; can be left out)
+	cache_path = "~/.cache/petrific.cache"
+
 	[signing]
 	# Use this GPG key to sign snapshots
 	key = "0123456789ABCDEF0123456789ABCDEF01234567"
diff --git a/cache/cache.go b/cache/cache.go
index 32b8325..2d20087 100644
--- a/cache/cache.go
+++ b/cache/cache.go
@@ -1,13 +1,20 @@
 package cache
 
 import (
+	"bufio"
 	"code.laria.me/petrific/objects"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
 	"time"
 )
 
 type Cache interface {
 	PathUpdated(path string) (mtime time.Time, id objects.ObjectId, ok bool)
 	SetPathUpdated(path string, mtime time.Time, id objects.ObjectId)
+	Close() error
 }
 
 type NopCache struct{}
@@ -18,3 +25,110 @@ func (NopCache) PathUpdated(_ string) (_ time.Time, _ objects.ObjectId, ok bool)
 }
 
 func (NopCache) SetPathUpdated(_ string, _ time.Time, _ objects.ObjectId) {}
+
+func (NopCache) Close() error { return nil }
+
+type fileCacheEntry struct {
+	mtime time.Time
+	id    objects.ObjectId
+}
+
+type FileCache struct {
+	cache    map[string]fileCacheEntry
+	location string
+}
+
+func (fc FileCache) PathUpdated(path string) (time.Time, objects.ObjectId, bool) {
+	entry, ok := fc.cache[path]
+	return entry.mtime, entry.id, ok
+}
+
+func (fc FileCache) SetPathUpdated(path string, mtime time.Time, id objects.ObjectId) {
+	fc.cache[path] = fileCacheEntry{mtime, id}
+}
+
+func NewFileCache(location string) FileCache {
+	return FileCache{make(map[string]fileCacheEntry), location}
+}
+
+func escapeName(name string) string {
+	name = strings.Replace(name, "\\", "\\\\", -1)
+	name = strings.Replace(name, "\n", "\\n", -1)
+	return name
+}
+
+func unescapeName(name string) string {
+	name = strings.Replace(name, "\\n", "\n", -1)
+	name = strings.Replace(name, "\\\\", "\\", -1)
+	return name
+}
+
+func (fc FileCache) dump(w io.Writer) error {
+	for path, entry := range fc.cache {
+		if _, err := fmt.Fprintf(
+			w,
+			"%s %d %d %s\n",
+			entry.id,
+			entry.mtime.Unix(),
+			entry.mtime.Nanosecond(),
+			escapeName(path),
+		); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (fc FileCache) load(r io.Reader) error {
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		parts := strings.SplitN(scanner.Text(), " ", 4)
+		if len(parts) != 4 {
+			return fmt.Errorf("Could not load FileCache: Expected 4 entries, got %d", len(parts))
+		}
+
+		id, err := objects.ParseObjectId(parts[0])
+		if err != nil {
+			return err
+		}
+
+		sec, err := strconv.ParseInt(parts[1], 10, 64)
+		if err != nil {
+			return err
+		}
+
+		nsec, err := strconv.ParseInt(parts[2], 10, 64)
+		if err != nil {
+			return err
+		}
+
+		fc.cache[unescapeName(parts[3])] = fileCacheEntry{time.Unix(sec, nsec), id}
+	}
+
+	return scanner.Err()
+}
+
+func (fc FileCache) Load() error {
+	f, err := os.Open(fc.location)
+	switch {
+	case os.IsNotExist(err):
+		return nil
+	case err != nil:
+		return err
+	default:
+	}
+	defer f.Close()
+
+	return fc.load(f)
+}
+
+func (fc FileCache) Close() error {
+	f, err := os.Create(fc.location)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return fc.dump(f)
+}
diff --git a/config/config.go b/config/config.go
index b643477..7deef69 100644
--- a/config/config.go
+++ b/config/config.go
@@ -11,6 +11,9 @@
 //    # This config key defines the default storage backend, as defined below ([storage.local_compressed])
 //    default_storage = "local_compressed"
 //
+//    # This defines the location of the cache file (can speed up creating backups; can be left out)
+//    cache_path = "~/.cache/petrific.cache"
+//
 //    [signing]
 //    # Use this GPG key to sign snapshots
 //    key = "0123456789ABCDEF0123456789ABCDEF01234567"
@@ -55,6 +58,7 @@ var (
 )
 
 type Config struct {
+	CachePath      string `toml:"cache_path,omitempty"`
 	DefaultStorage string `toml:"default_storage"`
 	Signing        struct {
 		Key string
diff --git a/main.go b/main.go
index 11202f3..5ea627f 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"code.laria.me/petrific/cache"
 	"code.laria.me/petrific/config"
 	"code.laria.me/petrific/storage"
 	"code.laria.me/petrific/storage/registry"
@@ -44,6 +45,7 @@ var (
 
 var conf config.Config
 var objectstore storage.Storage
+var id_cache cache.Cache = cache.NopCache{}
 
 func main() {
 	os.Exit(Main())
@@ -64,6 +66,11 @@ func Main() int {
 	}
 	defer objectstore.Close()
 
+	if !loadCache(conf) {
+		return 1
+	}
+	defer id_cache.Close()
+
 	remaining := make([]string, 0)
 	for _, arg := range flag.Args() {
 		if arg != "" {
@@ -84,6 +91,22 @@ func Main() int {
 	return cmd(remaining[1:])
 }
 
+func loadCache(conf config.Config) bool {
+	if conf.CachePath == "" {
+		return true
+	}
+
+	file_cache := cache.NewFileCache(config.ExpandTilde(conf.CachePath))
+	if err := file_cache.Load(); err != nil {
+		fmt.Fprintf(os.Stderr, "Loading cache %s: %s", conf.CachePath, err)
+		return false
+	}
+
+	id_cache = file_cache
+
+	return true
+}
+
 func loadConfig() bool {
 	var err error
 	conf, err = config.LoadConfig(*flagConfPath)
diff --git a/snapshot.go b/snapshot.go
index 844a85a..db181ba 100644
--- a/snapshot.go
+++ b/snapshot.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"code.laria.me/petrific/backup"
-	"code.laria.me/petrific/cache"
 	"code.laria.me/petrific/fs"
 	"code.laria.me/petrific/gpg"
 	"code.laria.me/petrific/objects"
@@ -115,7 +114,7 @@ func TakeSnapshot(args []string) int {
 		return 1
 	}
 
-	tree_id, err := backup.WriteDir(objectstore, dir_path, d, cache.NopCache{})
+	tree_id, err := backup.WriteDir(objectstore, dir_path, d, id_cache)
 	if err != nil {
 		errout(err)
 		return 1
diff --git a/write_dir.go b/write_dir.go
index 34abcd1..3ee5a97 100644
--- a/write_dir.go
+++ b/write_dir.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"code.laria.me/petrific/backup"
-	"code.laria.me/petrific/cache"
 	"code.laria.me/petrific/fs"
 	"fmt"
 	"os"
@@ -46,7 +45,7 @@ func WriteDir(args []string) int {
 		return 1
 	}
 
-	id, err := backup.WriteDir(objectstore, dir_path, d, cache.NopCache{})
+	id, err := backup.WriteDir(objectstore, dir_path, d, id_cache)
 	if err != nil {
 		errout(err)
 		return 1